Quantity is a guess. I thought there were more but only 3 heads came up.

Botanical name: Allium atropurpureum
Other names: Allium atropurpureum
Genus: Allium
Species: A. atropurpureum – A. atropurpureum is a bulbous perennial. It has basal, strap-shaped leaves and in late spring and early summer bears spherical, deep purple flowers on upright stems.
Allium atropurpureum is: Deciduous
Flower: Purple in Spring; Purple in Summer
Foliage: Grey-green in Spring; Grey-green in Summer
Habit: Erect

Pests: Pest free, may suffer from slugs on new growth.
Specific diseases: Onion rot , Downy mildew

Pruning: Cut back leaves only when they have completely died down.
Propagation methods: Division, Seed-September, October
Cut back after flowering in early autumn (optional)-September, October
Separate offsets -October
Plant 10cm deep in any moderately fertile, humus-rich, well-drained soil Any time
Sow seed in containers in cold frame (anytime)
Height of 0.5m and a spread of 0.5m after 2-5 years.

Cultivation: Grow in fertile, but well-drained soil. Add grit to clay soils to improve drainage. Acid, Alkaline, Neutral
Light: Full Sun
Aspect: South, East, West
Exposure: Sheltered
Hardiness: Hardy (H4)

Note: 15 from Klondyke Autumn 2009, also 50+ mail order Aug 2010